State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, China.
Environ Sci Technol. 2009 Oct 15;43(20):7734-41. doi: 10.1021/es9014458.
It was reported in our previous publication that the accumulation of short-chain fatty acids (SCFA) was significantly enhanced when waste-activated sludge (WAS) was anaerobically fermented at pH 10.0 (Yuan, et al., Environ. Sci. Technol. 2006, 40, 2025-2029). In this paper, the production of polyhydroxyalkanoate (PHA) by activated sludge with an aerobic feeding and discharge (AFD) process was investigated by the use of WAS alkaline fermentation liquid as the carbon source. It was observed that compared with other PHA synthesis processes reported in the literature, the AFD process showed the highest PHA production. The PHA content in sludge reached 72.9% when activated sludge was submitted to the AFD process. This was the highest PHA content obtained so far by activated sludge using wastes as the renewable carbon source. Although nitrogen and phosphorus were released into the WAS alkaline fermentation liquid, their presence did not affect PHA synthesis, which indicates that it is unnecessary to remove the released nitrogen and phosphorus, and the fermentation liquid can be used directly for PHA production. The accumulated PHAwas mainly composed of 3-hydroxybutyrate (3HB) (73.5 mmol C%), 3-hydroxyvalerate (3HV) (24.3 mmol C%), and 3-hydroxy-2-methylvalerate (3H2MV) (2.2 mmol C%). Further investigation showed that SCFA rather than protein and carbohydrate in the alkaline fermentation liquid made the main contribution to PHA production. The PHA produced from WAS alkaline fermentation liquid had a molecular weight of 8.5 x 10(5) Da and a melting point of 101.4 degrees C. Analysis using the 16S rRNA gene clone library revealed that gamma-Proteobacteria, alpha-Proteobacteria, and beta-Proteobacteria were the dominant microorganisms in the PHA production system.
在我们之前的出版物中报道过，当废活性污泥（WAS）在 pH 值为 10.0 时进行厌氧发酵时，短链脂肪酸（SCFA）的积累显著增加（Yuan 等人，环境科学与技术，2006，40，2025-2029）。在本文中，使用 WAS 碱性发酵液作为碳源，研究了好氧进料和排放（AFD）工艺中活性污泥产生聚羟基烷酸（PHA）的情况。与文献中报道的其他 PHA 合成工艺相比，AFD 工艺表现出最高的 PHA 产量。当活性污泥采用 AFD 工艺时，污泥中的 PHA 含量达到 72.9%。这是迄今为止使用废物作为可再生碳源的活性污泥获得的最高 PHA 含量。尽管氮和磷被释放到 WAS 碱性发酵液中，但它们的存在并不影响 PHA 合成，这表明不需要去除释放的氮和磷，发酵液可以直接用于 PHA 生产。积累的 PHA 主要由 3-羟基丁酸（3HB）（73.5 mmol C%）、3-羟基戊酸（3HV）（24.3 mmol C%）和 3-羟基-2-甲基戊酸（3H2MV）（2.2 mmol C%）组成。进一步的研究表明，碱性发酵液中的 SCFA 而不是蛋白质和碳水化合物是 PHA 生产的主要贡献者。从 WAS 碱性发酵液中生产的 PHA 的分子量为 8.5 x 10(5) Da，熔点为 101.4 摄氏度。使用 16S rRNA 基因克隆文库进行的分析表明，γ-变形菌、α-变形菌和β-变形菌是 PHA 生产系统中的主要微生物。
